Control system for machine having rotary cutting head

Abstract

A control system may be provided for operating a machine having a rotary cutting head. The control system may include a wrist capable of rotating about a wrist axis, a gear mechanism capable of driving rotation of the wrist. A cutting head may be attached to the wrist and capable of rotating about a cutter axis that is substantially perpendicular to the wrist axis. The control system may also include primary and redundant angular sensors capable of generating signals indicative of angular orientations of the wrist. The control system may additionally include a controller, capable of controlling operation of the wrist and the cutting head, comparing an actual angular orientation of the wrist to a target angular orientation, as indicated by the primary and secondary signals, and selectively inhibiting the cutting head from operating when the actual angular orientation differs from the target angular orientation by an operation threshold.

What is claimed is: 
     
         1 . A control system for a machine, the control system comprising:
 a wrist configured to rotate about a wrist axis;   a gear mechanism configured to drive rotation of the wrist;   a cutting head coupled to the wrist and configured to rotate about a cutter axis that is substantially perpendicular to the wrist axis;   a primary angular sensor configured to generate primary signals indicative of angular orientations of the wrist;   at least one redundant angular sensor configured to generate secondary signals indicative of angular orientations of the wrist; and   a controller configured to:
 control operation of the wrist and the cutting head; 
 compare an actual angular orientation of the wrist, as indicated by one or more of the primary signals or the secondary signals, to a target angular orientation; and 
 selectively inhibit the cutting head from operating when the controller determines that the actual angular orientation differs from the target angular orientation by an operation threshold. 
   
     
     
         2 . The control system of  claim 1 , wherein the controller is further configured to control operation of the wrist based on only one or more of the primary signals. 
     
     
         3 . The control system of  claim 1 , wherein the controller is further configured to control operation of the wrist based on only the secondary signals when the primary signals are unavailable and when the primary signals are out of range. 
     
     
         4 . The control system of  claim 1 , further including a display in communication with the controller, wherein the controller is configured to:
 compare the primary signals and the secondary signals to an expectation value, and   selectively cause a specific sensor warning to be shown on the display when the controller determines that at least one of the primary signals or the secondary signals differs from the expectation value by an expectation threshold.   
     
     
         5 . The control system of  claim 1 , further including a display in communication with the controller, wherein the controller is configured to selectively cause a signal warning to be shown on the display when the controller determines the primary signals are unavailable and when the controller determines the primary signals are out of range. 
     
     
         6 . The control system of  claim 1 , further including a display in communication with the controller, wherein the controller is configured to:
 compare the primary signals to the secondary signals;   selectively inhibit the cutting head from operating when the controller determines that the primary signals differ from the secondary signals by the operation threshold; and   selectively cause a calibration instruction to be shown on the display when the controller determines that the primary signals differ from the secondary signals by a signal threshold.   
     
     
         7 . The control system of  claim 1 , further including a display in communication with the controller, wherein the controller is configured to selectively cause a warning to be shown on the display when the controller determines that the actual angular orientation differs from the target angular orientation by a warning threshold that is lower than the operation threshold. 
     
     
         8 . The control system of  claim 1 , further including an environment sensor in communication with the controller and configured to generate environment signals, wherein the controller is further configured to:
 compare an actual angular orientation of the wrist, as provided via the environment signals, to the target angular orientation; and   selectively inhibit the cutting head from operating when the controller determines that the actual angular orientation differs from the target angular orientation by the operation threshold.   
     
     
         9 . The control system of  claim 1 , wherein the target angular orientation is a preferred orientation in which an axial end face of the cutting head is perpendicular to an operation milling direction. 
     
     
         10 . A method for operating a cutting head of a machine, the method comprising:
 determining a target angular orientation of the cutting head;   generating a primary angular orientation output associated with the cutting head;   generating a redundant angular orientation output associated with the cutting head;   making a first comparison of the primary angular orientation output to the target angular orientation; and   selectively inhibiting the cutting head from operating based on the first comparison when the primary angular orientation output and the target angular orientation differ by an operation threshold.   
     
     
         11 . The method of  claim 10 , further including:
 making a second comparison of the redundant angular orientation output to the target angular orientation only when the primary angular orientation output is unavailable and when the primary angular orientation output is out of range; and   selectively inhibiting the cutting head from operating based on the second comparison when the redundant angular orientation output and the target angular orientation differs by the operation threshold.   
     
     
         12 . The method of  claim 11 , further including displaying a second warning when the redundant angular orientation output and the target angular orientation differs by a warning threshold that is lower than the operation threshold. 
     
     
         13 . The method of  claim 10 , further including:
 generating an environment angular orientation output associated with the cutting head;   making a third comparison of the environment angular orientation output to the target angular orientation; and   selectively inhibiting the cutting head from operating based on the third comparison when the environment angular orientation output and the target angular orientation differs by the operation threshold.   
     
     
         14 . The method of  claim 10 , further including displaying a signal warning when the primary orientation output is unavailable and when the primary orientation output is out of range. 
     
     
         15 . The method of  claim 10 , further including:
 comparing the primary angular orientation output to the redundant angular orientation output;   selectively inhibiting the cutting head from operating based on the third comparison when the environment angular orientation output and the target angular orientation differs by the operation threshold; and   displaying a calibration instruction when the primary orientation output and the redundant orientation output differs by a signal threshold.   
     
     
         16 . The method of  claim 10 , further including:
 comparing the primary angular orientation output to the redundant angular orientation output; and   displaying a second warning when the primary angular orientation output and the target angular orientation differs by a warning threshold that is lower than the operation threshold   
     
     
         17 . A machine, comprising:
 a wrist configured to rotate about a wrist axis;   a gear mechanism configured to drive rotation of the wrist and having an exposed surface with a plurality of angular markings;   a stationary surface adjacent the gear mechanism and having a reference marking;   a cutting head coupled to the wrist and configured to rotate about a cutter axis that is substantially perpendicular to the wrist axis;   a primary encoder disposed in the gear mechanism and configured to generate primary signals indicative of angular orientations of the wrist;   at least one redundant encoder disposed in the gear mechanism and configured to generate secondary signals indicative of the angular orientations of the wrist; and   a controller configured to:
 control operation of the wrist and the cutting head; 
 compare an actual angular orientation of the wrist, as indicated by one or more of the primary signals or the secondary signals, to a target angular orientation; 
 compare the primary signals to the secondary signals; 
 selectively inhibit the cutting head from operating when the controller determines that the actual angular orientation differs from the target angular orientation by an operation threshold and when the controller determines that the primary signals differ from the secondary signals by the operation threshold; 
 selectively cause a calibration instruction to be shown on a display when the controller determines the primary signals differ from the secondary signals by a signal threshold; and 
 selectively cause a warning to be shown on the display when the controller determines the actual angular orientation differs from the target angular orientation by a warning threshold that is lower than the operation threshold. 
   
     
     
         18 . The control system of  claim 17 , wherein the controller is further configured to control operation of the wrist based on only the primary signals as long as the primary signals are available and within range. 
     
     
         19 . The control system of  claim 18 , wherein the controller is further configured to control operation of the wrist based on only the secondary signals when the controller determines the primary signals are unavailable and when the controller determines the primary signals are out of range. 
     
     
         20 . The control system of  claim 17 , further including an environment sensor in communication with the controller and configured to generate environment signals, wherein the controller is further configured to:
 compare an actual angular orientation of the wrist, as provided via the environment signals, to the target angular orientation; and   selectively inhibit the cutting head from operating when the controller determines that the actual angular orientation differs from the target angular orientation by the operation threshold.